It can be done but the process is quite tedious. You have to have Feedburner grab your feed, then go to the Feedburner site and look at your feed there, copy the email link and post it into your post. (The exact instructions are in the forums under the sphere widget discussion.) I found it not worth the effort.

he or she will be able to email any page by clicking a bookmark in a browser. It's just javascript code to create a button in your bookmarks or favorites. I tried to get it to work as a form button or hyperlink on my wordpress site but so far I've been unsuccessful. As for privacy concerns emailing people using the clickability service, I was "referred" by CNN.com; they have clickability links on their news articles. I registered a year ago but don't get any inordinate amounts of spam so I feel pretty safe. And registering is not required; of course they have your email either way.

So the answer? Direct users to that link, have them add the button, come back, then use it on the same page they are visiting. :) Getting closer! Seems very odd that wp doesn't have this option, but it could be a security issue, or concerns about a flood of email--even if it's not spam--being sent using their servers. I'm done searching for now. I guess I should have tried the FAQ and not limited myself to the forum. At least I'm thinking now, even if it was delayed.